The art of manufacturing fabrics using silk which is a natural material has been traditionally succeeded. The fabrics have specific feeling, beautiful gloss and softness, in particular both air-permeability and hygroscopicity properties.
The silk yarn comprises a pair of fibroin portions, which is covered with an outer layer of sericin. The so-called "silk products" are manufactured by removing sericin which is a glue type protein from the silk yarns and weaving or knitting the sericin-removed silk yarns. It is deemed that the fibroin which is one of the components of silk product consists of a plurality of fibril molecules which are ester-bonded to each other. The silk products have various problems since the bond between the fibril molecules is weak. The silk fibers as natural material have not been scientifically researched completely and has a number of various unknown subjects.
The same applies to cellulose fibers (including cellulose fiber yarns) which are also manufactured from natural materials.
The present invention enhances shrink and crease resistance and shape stability of the silk yarn, cellulose fibers and their twisted yarns of their conjugate fibers by treating and finishing them using a sericin fixing method to form a skeleton of triazine or triazine bond in the fibers. Now, the properties of woven or knitted fabrics made from the inventive yarns and fibers will be shown.
There have been proposed various finishing and treating processes for conducting a method of fixing the sericin of the raw silk. A number of various solvents have been developed for these processes. However, the sericin which is a glue like protein provides hard touch and low gloss. If the raw silk is dyed, the sericin would be dissolved, resulting in that it will become hard to use the raw silk as garment fibers.
Accordingly, use of the sericin fixed type raw silk is limited to only special fabrics referred to as "kiginu" (unscoured silk) such as fabrics of silk organsee, chiffon, bolting cloth, Fuji silk. They have appearance, touch and characteristics which are different from those of the woven or knitted fabrics made from fibroin silk in which the sericin has been removed by dissolution.
Some of the sericin fixing methods use the materials as follows:
1. aldehydes PA1 2. heavy metal salts PA1 3. tannin PA1 4. synthetic resins melamines, DMNFU, epoxides PA1 5. cyanuric chloride and dichlorotriazine type reactive dyes
formalin, glutaric aldehyde, dialdehyde starch, acrylic aldehyde PA2 chrome alum, dichromic acid salts+reducing agent, aluminum alum, acrylic aldehyde
It has heretofore been proved that the methods using formalin, glutaric aldelhydes, chrome salts, and cyanutic chloride and dichlorotriazine type reactive dyes of the above-mentioned sericin fixing methods are most practical.
However, the method using formalin is not preferred since formalin gives a strong influence upon human body so that it is harmful. The method using chrome salts may cause environmental pollution by its industrial wastes and epoxide resins has problems that its working is unstable and it has a fear of influence to human body such as skin disease. Therefore, the foregoing method are not the best way.
The present invention adopts a sericin fixing method relying on formation of a skeleton triazine of cyanuric chlorides which do not have the above-mentioned problems.
It has been proved that the sericin will react with fibroin protein in an efficient manner in a method of forming skeleton triazine. It is deemed that the skeleton triazine in the sericin fixing method is represented by following chemical structures (refer to Japanese Examined Patent Publication No. Tokkosho 40-8050). ##STR1##
An invention which is disclosed in Japanese Patent No. 2559302 (Japanese Unexamined Patent Publication No. Tokkaihei 4-300359) is an improvement in the invention of the Japanese Examined Patent Publication No. Tokkosho 40-8050).
In brief, the invention disclosed in the Japanese Examined Patent Publication No. Tokkosho 40-8050 proposes a sericin fixing method for fixing sericin in raw silk so that the sericin will not be dissolved in usual scouring (using hot water), soap scouring and alkaline scouring. The invention of Japanese Patent No. 2559302 proposes a method of finishing fibroin (silk) in which sericin has been removed.
A sericin fixing method using a reactive dye of cyanuric acid salt (cyanurate) or its derivatives or cyanuric acid derivatives is disclosed in Japanese Examined Patent Publication No. Tokkosho 40-8050. As mentioned above, the silk fabrics and silk fibers are covered on their surface thereof with sericin. The sericin shall be dissolved from the silk fabrics on soap or alkaline scouring if they have not been subjected to the sericin fixing method. However, specific fabrics, organsee or ornamental fabrics are preferably used while touch of the cloth is hard. Accordingly, it is necessary to fix the sericin so that it is hard to be dissolved on soap and alkaline scouring. National Institute of Agricultural Science of Sericultural and Insects, Ministry of Agricultural and Forestry has conducted research and development of materials having unique feeling relying on the characteristics of the sericin fixed fabrics and made a report on characteristics of their materials (refer to 47th Nissan Kanto, 1996, pages 82 to 83). The report says that fabrics were made by using mono-and dichlorotriazine type reactive dyes and various their characteristics were measured. Regarding the result of crease resistance, the recovery ratio of crease becomes low as the residual degree of the sericin becomes high.
The above-mentioned Japanese Examined Patent Publication No. Tokkosho 40-8050 was cited as a reference in the course of examination of the Japanese patent No. 2559302 entitled "composition for modifying of silk products and processes for the modification". In this invention, the object to be modified is defined as piece dyed type silk products which are dyed after removing sericin, that is the silk products made of only fibroin. The reason why the process of this invention is restricted to the piece dyed type silk products in order to avoid the problem inhering to the inventive product of the Japanese Examined Patent Publication No. Tokkosho 40-8050 is deemed as follows: In order to form a skeleton triazine, sericin fixing is conducted by applying 1% by weight of cyanuric chloride to the raw silk and using ethylenetetrachloride as a solvent.
However, cold water can not be used since cyanuric chloride is insoluble to the cold water. Ethylenetetrachloride, 1:1:2:2. tetrachloro-ethane and the like may be used as its solvent. Their derivatives are hard to be used since they have irritating odor like chloroform. It has been found that fixing of sericin for raw silk makes the sericin insoluble on usual soap and alkaline scouring. The fact that the recovery power of the crease is less if the sericin is not sufficiently dissolved so that it remains has been proved as mentioned above. Accordingly, the invention of the Japanese Patent No. 2559302 modifies by the cross linking reaction with fibroin the rubbing which occurs in thee course of manufacturing of the silk fabric made of only fibroin, in which sericin is dissolved out on usual soap and alkaline scouring.